ISSN:
1432-1440
Keywords:
Vitamin Q
;
Vitamin E
;
Coenzyme Q
;
Ubiquinone
;
α-tocopherol
;
Normalized plasma VQ and AT
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Ubiquinone (UQ) and α-tocopherol (AT) are two highly lipophilic antioxidants which can be dissolved only in lipid layers or attached to protein structures. Analyses of both UQ and AT in whole blood and plasma demonstrate identical values, which excludes any significant allocation to blood cells. The lipoidic plasma structures constitute the plasma lipoprotein fractions of high (HDL), low (LDL), and very low (VLDL) density in addition to chylomicrons. This means by definition that blood and plasma UQ and AT values are limited if not related to the lipoidic deposit volume. UQ and AT increase linearly with free cholesterol (FC). FC has therefore been suggested to be a good marker for the deposit volume. The ratios UQ and AT over FC - normalized UQ (N-UQ) and normalized AT (N-AT) - have been computed for inter-and intraindividual comparisons. With a plasma UQ content of 1 μg/ml (≈ 1 μmol/l) and a plasma volume of 41, UQ makes up about 15% of the total heart content or under 1% of UQ in skeletal muscle. The corresponding value for the total extracellular UQ content is less than 2%. This means that extracellular UQ has no or a very minor role as a UQ depot. The same is true for AT. However, for transportation and allocation determinations of N-UQ and N-AT are relevant. Assuming only a lipoprotein-related transportation, healthy persons have saturated plasma UQ and AT values in only 25% and 10% of the population, respectively. All patient categories studied have been found nonsaturated. VLDL plus LDL constitute some 90% of the UQ deposit volume. VLDL and LDL are released from the liver to transport fat, for example, to muscle tissue. HDL has a corresponding cholesterol-transporting function. Uptake depends on the local lipoprotein lipase activity. Do these transports also function as means for UQ and AT transport? Per unit of FC, UQ content in VLDL+LDL is about five times that in HDL. The corresponding AT value is about unity. This difference between UQ and AT storage does not exclude the possibility that VLDL+LDL particles possess the ability to transport UQ between different compartments when so necessary.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00226846
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